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  • 1
    Publication Date: 2002-05-23
    Description: The crystal structure of the initiating form of Thermus aquaticus RNA polymerase, containing core RNA polymerase (alpha2betabeta'omega) and the promoter specificity sigma subunit, has been determined at 4 angstrom resolution. Important structural features of the RNA polymerase and their roles in positioning sigma within the initiation complex are delineated, as well as the role played by sigma in modulating the opening of the RNA polymerase active-site channel. The two carboxyl-terminal domains of sigma are separated by 45 angstroms on the surface of the RNA polymerase, but are linked by an extended loop. The loop winds near the RNA polymerase active site, where it may play a role in initiating nucleotide substrate binding, and out through the RNA exit channel. The advancing RNA transcript must displace the loop, leading to abortive initiation and ultimately to sigma release.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murakami, Katsuhiko S -- Masuda, Shoko -- Darst, Seth A -- GM53759/GM/NIGMS NIH HHS/ -- GM61898/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2002 May 17;296(5571):1280-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12016306" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Motifs ; Binding Sites ; Crystallization ; Crystallography, X-Ray ; DNA, Bacterial/metabolism ; DNA-Directed RNA Polymerases/*chemistry/*metabolism ; Eukaryotic Cells/metabolism ; Holoenzymes/chemistry/metabolism ; Models, Molecular ; Promoter Regions, Genetic ; Protein Conformation ; Protein Structure, Quaternary ; Protein Structure, Secondary ; Protein Structure, Tertiary ; RNA, Bacterial/metabolism ; RNA, Messenger/metabolism ; Sigma Factor/metabolism ; Thermus/*enzymology ; *Transcription, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2002-05-23
    Description: The crystal structure of Thermus aquaticus RNA polymerase holoenzyme (alpha2betabeta'omegasigmaA) complexed with a fork-junction promoter DNA fragment has been determined by fitting high-resolution x-ray structures of individual components into a 6.5-angstrom resolution map. The DNA lies across one face of the holoenzyme, completely outside the RNA polymerase active site channel. All sequence-specific contacts with core promoter elements are mediated by the sigma subunit. A universally conserved tryptophan is ideally positioned to stack on the exposed face of the base pair at the upstream edge of the transcription bubble. Universally conserved basic residues of the sigma subunit provide critical contacts with the DNA phosphate backbone and play a role in directing the melted DNA template strand into the RNA polymerase active site. The structure explains how holoenzyme recognizes promoters containing variably spaced -10 and -35 elements and provides the basis for models of the closed and open promoter complexes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murakami, Katsuhiko S -- Masuda, Shoko -- Campbell, Elizabeth A -- Muzzin, Oriana -- Darst, Seth A -- GM20470/GM/NIGMS NIH HHS/ -- GM53759/GM/NIGMS NIH HHS/ -- GM61898/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2002 May 17;296(5571):1285-90.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12016307" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; Crystallization ; Crystallography, X-Ray ; DNA, Bacterial/*chemistry/genetics/metabolism ; DNA-Directed RNA Polymerases/*chemistry/metabolism ; Holoenzymes/chemistry/metabolism ; Models, Molecular ; Nucleic Acid Conformation ; *Promoter Regions, Genetic ; Protein Conformation ; Protein Structure, Quaternary ; Protein Structure, Secondary ; Protein Subunits ; Sigma Factor/*chemistry/metabolism ; Templates, Genetic ; Thermus/*enzymology ; *Transcription, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2008-02-01
    Description: The transcription apparatus in Archaea can be described as a simplified version of its eukaryotic RNA polymerase (RNAP) II counterpart, comprising an RNAPII-like enzyme as well as two general transcription factors, the TATA-binding protein (TBP) and the eukaryotic TFIIB orthologue TFB. It has been widely understood that precise comparisons of cellular RNAP crystal structures could reveal structural elements common to all enzymes and that these insights would be useful in analysing components of each enzyme that enable it to perform domain-specific gene expression. However, the structure of archaeal RNAP has been limited to individual subunits. Here we report the first crystal structure of the archaeal RNAP from Sulfolobus solfataricus at 3.4 A resolution, completing the suite of multi-subunit RNAP structures from all three domains of life. We also report the high-resolution (at 1.76 A) crystal structure of the D/L subcomplex of archaeal RNAP and provide the first experimental evidence of any RNAP possessing an iron-sulphur (Fe-S) cluster, which may play a structural role in a key subunit of RNAP assembly. The striking structural similarity between archaeal RNAP and eukaryotic RNAPII highlights the simpler archaeal RNAP as an ideal model system for dissecting the molecular basis of eukaryotic transcription.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2805805/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2805805/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hirata, Akira -- Klein, Brianna J -- Murakami, Katsuhiko S -- R01 GM071897/GM/NIGMS NIH HHS/ -- R01 GM071897-04/GM/NIGMS NIH HHS/ -- England -- Nature. 2008 Feb 14;451(7180):851-4. doi: 10.1038/nature06530. Epub 2008 Jan 30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18235446" target="_blank"〉PubMed〈/a〉
    Keywords: Crystallography, X-Ray ; DNA-Directed RNA Polymerases/*chemistry/metabolism ; Iron-Sulfur Proteins/chemistry/metabolism ; Models, Molecular ; Protein Folding ; Protein Structure, Tertiary ; Protein Subunits/chemistry/metabolism ; Saccharomyces cerevisiae/enzymology ; Sulfolobus solfataricus/*enzymology ; Taq Polymerase/chemistry
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2015-08-22
    Description: Transcription by RNA polymerase (RNAP) in bacteria requires specific promoter recognition by sigma factors. The major variant sigma factor (sigma(54)) initially forms a transcriptionally silent complex requiring specialized adenosine triphosphate-dependent activators for initiation. Our crystal structure of the 450-kilodalton RNAP-sigma(54) holoenzyme at 3.8 angstroms reveals molecular details of sigma(54) and its interactions with RNAP. The structure explains how sigma(54) targets different regions in RNAP to exert its inhibitory function. Although sigma(54) and the major sigma factor, sigma(70), have similar functional domains and contact similar regions of RNAP, unanticipated differences are observed in their domain arrangement and interactions with RNAP, explaining their distinct properties. Furthermore, we observe evolutionarily conserved regulatory hotspots in RNAPs that can be targeted by a diverse range of mechanisms to fine tune transcription.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4681505/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4681505/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yang, Yun -- Darbari, Vidya C -- Zhang, Nan -- Lu, Duo -- Glyde, Robert -- Wang, Yi-Ping -- Winkelman, Jared T -- Gourse, Richard L -- Murakami, Katsuhiko S -- Buck, Martin -- Zhang, Xiaodong -- 098412/Wellcome Trust/United Kingdom -- BB/C504700/1/Biotechnology and Biological Sciences Research Council/United Kingdom -- GM087350/GM/NIGMS NIH HHS/ -- R01 GM087350/GM/NIGMS NIH HHS/ -- R37 GM37048/GM/NIGMS NIH HHS/ -- Biotechnology and Biological Sciences Research Council/United Kingdom -- New York, N.Y. -- Science. 2015 Aug 21;349(6250):882-5. doi: 10.1126/science.aab1478.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Centre for Structural Biology, Imperial College London, South Kensington SW7 2AZ, UK. State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, China. ; Centre for Structural Biology, Imperial College London, South Kensington SW7 2AZ, UK. Department of Medicine, Imperial College London, South Kensington SW7 2AZ, UK. ; Department of Life Sciences, Imperial College London, South Kensington SW7 2AZ, UK. ; Centre for Structural Biology, Imperial College London, South Kensington SW7 2AZ, UK. ; State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, China. ; Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA. ; Department of Biochemistry and Molecular Biology, Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA. ; Centre for Structural Biology, Imperial College London, South Kensington SW7 2AZ, UK. Department of Medicine, Imperial College London, South Kensington SW7 2AZ, UK. xiaodong.zhang@imperial.ac.uk.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26293966" target="_blank"〉PubMed〈/a〉
    Keywords: Crystallography, X-Ray ; Enzyme Stability ; *Evolution, Molecular ; *Gene Expression Regulation ; Holoenzymes/chemistry ; Protein Conformation ; Protein Structure, Tertiary ; RNA Polymerase Sigma 54/*chemistry/genetics ; *Transcription, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2016-01-05
    Description: The averaged toroidal flow of energetic minority ions during ICRF (ion cyclotron range of frequencies) heating is investigated in the Alcator C-Mod plasma by applying the GNET code, which can solve the drift kinetic equation with complicated orbits of accelerated energetic particles. It is found that a co-directional toroidal flow of the minority ions is generated in the region outside of the resonance location, and that the toroidal velocity reaches more than 40% of the central ion thermal velocity ( V tor ∼ 300 km/s with P ICRF ∼ 2 MW). When we shift the resonance location to the outside of | r / a | ∼ 0.5 , the toroidal flow immediately inside of the resonance location is reduced to 0 or changes to the opposite direction, and the toroidal velocity shear is enhanced at r / a ∼ 0.5. A radial diffusion equation for toroidal flow is solved by assuming a torque profile for the minority ion mean flow, and good agreements with experimental radial toroidal flow profiles are obtained. This suggests that the ICRF driven minority ion flow is related to the experimentally observed toroidal rotation during ICRF heating in the Alcator C-Mod plasma.
    Print ISSN: 1070-664X
    Electronic ISSN: 1089-7674
    Topics: Physics
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  • 6
    Publication Date: 2010-12-27
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 7
    Publication Date: 2011-03-02
    Description: We have determined the X-ray crystal structures of the pre- and postcatalytic forms of the initiation complex of bacteriophage N4 RNA polymerase that provide the complete set of atomic images depicting the process of transcript initiation by a single-subunit RNA polymerase. As observed during T7 RNA polymerase transcript elongation, substrate loading for the initiation process also drives a conformational change of the O helix, but only the correct base pairing between the +2 substrate and DNA base is able to complete the O-helix conformational transition. Substrate binding also facilitates catalytic metal binding that leads to alignment of the reactive groups of substrates for the nucleotidyl transfer reaction. Although all nucleic acid polymerases use two divalent metals for catalysis, they differ in the requirements and the timing of binding of each metal. In the case of bacteriophage RNA polymerase, we propose that catalytic metal binding is the last step before the nucleotidyl transfer reaction.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 8
    Publication Date: 2011-04-06
    Description: Obesity and insulin resistance, the key features of metabolic syndrome, are closely associated with a state of chronic, low-grade inflammation characterized by abnormal macrophage infiltration into adipose tissues. Although it has been reported that chemokines promote leukocyte migration by activating class IB phosphoinositide-3 kinase (PI3Kγ) in inflammatory states, little is known about the role of PI3Kγ in obesity-induced macrophage infiltration into tissues, systemic inflammation, and the development of insulin resistance. In the present study, we used murine models of both diet-induced and genetically induced obesity to examine the role of PI3Kγ in the accumulation of tissue macrophages and the development of obesity-induced insulin resistance. Mice lacking p110γ (Pik3cg−/−), the catalytic subunit of PI3Kγ, exhibited improved systemic insulin sensitivity with enhanced insulin signaling in the tissues of obese animals. In adipose tissues and livers of obese Pik3cg−/− mice, the numbers of infiltrated proinflammatory macrophages were markedly reduced, leading to suppression of inflammatory reactions in these tissues. Furthermore, bone marrow-specific deletion and pharmacological blockade of PI3Kγ also ameliorated obesity-induced macrophage infiltration and insulin resistance. These data suggest that PI3Kγ plays a crucial role in the development of both obesity-induced inflammation and systemic insulin resistance and that PI3Kγ can be a therapeutic target for type 2 diabetes.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 9
    Publication Date: 2011-01-12
    Description: Spt4/5 in archaea and eukaryote and its bacterial homolog NusG is the only elongation factor conserved in all three domains of life and plays many key roles in cotranscriptional regulation and in recruiting other factors to the elongating RNA polymerase. Here, we present the crystal structure of Spt4/5 as well as the structure of RNA polymerase-Spt4/5 complex using cryoelectron microscopy reconstruction and single particle analysis. The Spt4/5 binds in the middle of RNA polymerase claw and encloses the DNA, reminiscent of the DNA polymerase clamp and ring helicases. The transcription elongation complex model reveals that the Spt4/5 is an upstream DNA holder and contacts the nontemplate DNA in the transcription bubble. These structures reveal that the cellular RNA polymerases also use a strategy of encircling DNA to enhance its processivity as commonly observed for many nucleic acid processing enzymes including DNA polymerases and helicases.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 10
    Publication Date: 2016-03-19
    Description: An ATP-dependent RNA ligase from Methanobacterium thermoautotrophicum (MthRnl) catalyzes intramolecular ligation of single-stranded RNA to form a closed circular RNA via covalent ligase-AMP and RNA-adenylylate intermediate. Here, we report the X-ray crystal structures of an MthRnl•ATP complex as well as the covalent MthRnl–AMP intermediate. We also performed structure-guided mutational analysis to survey the functions of 36 residues in three component steps of the ligation pathway including ligase-adenylylation (step 1), RNA adenylylation (step 2) and phosphodiester bond synthesis (step 3). Kinetic analysis underscored the importance of motif 1a loop structure in promoting phosphodiester bond synthesis. Alanine substitutions of Thr117 or Arg118 favor the reverse step 2 reaction to deadenylate the 5'-AMP from the RNA-adenylate, thereby inhibiting step 3 reaction. Tyr159, Phe281 and Glu285, which are conserved among archaeal ATP-dependent RNA ligases and are situated on the surface of the enzyme, are required for RNA binding. We propose an RNA binding interface of the MthRnl based on the mutational studies and two sulfate ions that co-crystallized at the active site cleft in the MthRnl–AMP complex.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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